Synthesis and Properties of Sulfur-Containing Organophosphorus Extractants Based on Red Phosphorus, Alkyl Bromides, and Elemental Sulfur.

In order to obtain sulfur-containing organophosphorus compounds that are promising as extractants of heavy metals, the interaction of elemental phosphorus and sulfur with alkyl bromides catalyzed using strong bases was studied. According to the task, the reaction of non-toxic and non-flammable red phosphorus with alkyl bromides under conditions of phase transfer catalysts (PTC), followed by the introduction of elemental sulfur into the reaction medium, were studied. It is shown that alkyl bromides interact with red phosphorus when heated (95-105 °C, 5-8 h) under conditions of phase transfer catalysts (PTC) in a two-phase system: a 60% aqueous solution of KOH-toluene-benzyltriethylammonium chloride (BTEAC) forming a mixture of organophosphorus compounds along with alkylphosphines (57-60%), are the main reaction products; alkylphosphine oxides are also formed (40-43%). The introduction of elemental sulfur (solution in toluene) at the final stage of the process into the reaction mass cooled to 40-60 °C leads to the expected alkylphosphine sulfides, which are the result of the interaction of alkylphosphines with sulfur. The formation of complex mixtures of products prevents the release of target alkylphosphine sulfides in individual form. However, the synthesized mixture of alkylphosphine sulfides and alkylphosphine oxides without separation into individual components is promising for studying its extraction properties in relation to heavy metals. Testing of the extraction properties of synthesized mixtures of alkylphosphine sulfides and alkylphosphine oxides in relation to heavy metals (Ni, Co, Zn, Pb) and noble metals (Ag) showed that the resulting mixtures of tertiary phosphine oxides and phosphine sulfides are highly effective extractants. The degree of extraction in relation to Ni, Co, Zn, and Pb varies from 99.90 to 99.99%, and for Ag from 99.56 to 99.59%.

Chemoselective synthesis of long-chain alkyl-H-phosphinic acids via one-pot alkylation/oxidation of red phosphorus with alkyl-PEGs as recyclable micellar catalysts.

Long-chain n-alkyl-H-phosphinic acids (Alk = C4-C18) are chemoselectively synthesized in yields up to 90% via the direct one-pot alkylation/oxidation of red phosphorus (Pn) in the multi-phase alkyl bromide/KOH/H2O/toluene system with alkyl-PEG recyclable micellar catalysts, which demonstrate good recyclability.

Oxidative cross-coupling of secondary phosphine chalcogenides with amino alcohols and aminophenols: aspects of the reaction chemoselectivity.

Secondary phosphine chalcogenides react with primary amino alcohols under mild conditions (room temperature, molar ratio of the initial reagents 1 : 1) in a CCl4/Et3N oxidizing system to chemoselectively deliver amides of chalcogenophosphinic acids with free OH groups. Under similar conditions, mono-cross-coupling between secondary phosphine chalcogenides and 1,2- or 1,3-aminophenols proceeds only with the participation of phenolic hydroxyl to give aminophenylchalcogenophosphinic O-esters. The yields of the synthesized functional amides or esters are 60-85%.

Catalyst-Free Double CH-Functionalization of Quinolines with Phosphine Oxides via Two SNHAr Reaction Sequences.

Quinolines undergo catalyst-free double CH-functionalization upon treatment with secondary phosphine oxides (70-75 °C, 20-48 h) followed by oxidation of the intermediate 2,4-bisphosphoryltetrahydroquinolines with chloranil. The yields of the target 2,4-bisphosphorylated quinolines are up to 77%. Thus, a double-SNHAr reaction sequence in the same molecule of quinoline has been realized. In the case of 2,4-bisphenylphosphoryltetrahydroquinolines, the aromatization occurs with elimination of one molecule of diphenylphosphine oxide to afford the products of monofunctionalization, 4-diphenylphosphorylquinolines, in 40-45% yields.

Acetylene-Triggered Reductive Incorporation of Phosphine Chalcogenides into a Quinoline Scaffold: Toward SNHAr Reaction.

Quinolines react with acylacetylenes and secondary phosphine chalcogenides at 20-75 °C to afford N-acylvinyl-2(1)-chalcogenophosphoryldihydroquinolines in good and excellent yields. Unlike the pyridine-derived similar intermediates, which eliminate E-alkenes to give aromatic chalcogenophosphorylpyridines, thereby completing SNHAr reaction, with quinolines, the reaction stops at the formation of the above phosphorylated N-acylvinyl-dihydroquinolines, thus representing a pendant SNHAr process. This reaction opens a one-pot atom-economic single-step access to pharmaceutically targeted phosphorylated functionalized dihydroquinolines and isoquinolines.

Catalyst-Free Phosphorylation of Acridine with Secondary Phosphine Chalcogenides: Nucleophilic Addition vs SNHAr Reaction.

Acridine adds secondary phosphine chalcogenides HP(X)R2 (X = O, S, Se; R = Ar, ArAlk) under catalyst-free conditions at 70-75 °C (both in the presence and absence of the electron-deficient acetylenes) to give 9-chalcogenophosphoryl-9,10-dihydroacridines in 61-94% yields. This contrasts with pyridines, which under similar conditions undergo an SNHAr reaction, wherein electron-deficient acetylenes play the role of oxidants. For acridine, the SNHAr step has been accomplished by the oxidation of the intermediate 9-phosphoryl-9,10-dihydroacridines (X = O) with chloranil.

Metal-free site selective cross-coupling of pyridines with secondary phosphine chalcogenides using acylacetylenes as oxidants.

Pyridines undergo site selective cross-coupling with secondary phosphine chalcogenides (oxides, sulfides, and selenides) in the presence of acylphenylacetylenes under metal-free mild conditions (70-75 °C, MeCN) to afford 4-chalcogenophosphoryl pyridines in up to 71% yield. In this new type of SNHAr reaction acylacetylenes act as oxidants, being stereoselectively reduced to the corresponding olefins of the E-configuration.

Aerobic addition of secondary phosphine oxides to vinyl sulfides: a shortcut to 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides.

Secondary phosphine oxides react with vinyl sulfides (both alkyl- and aryl-substituted sulfides) under aerobic and solvent-free conditions (80 °C, air, 7-30 h) to afford 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides in 70-93% yields.

Dinuclear gold(I) dithio- and diselenophosph(in)ate complexes forming mononuclear gold(III) oxidative addition complexes and reversible chemical reductive elimination products.

Dinuclear gold(i) dithio- and diselenophosph(in)ate complexes were prepared to serve as precursors for subsequent oxidative addition (OA) chemistry following reaction with mild oxidant iodine, I2. The new OA products circumvented the formation of the expected dinuclear Au(ii) complexes, but instead formed novel chelating mononuclear square-planar gold(iii) products of the type [AuI2{E2PR2}] (R = (CH2)2Ph; E = S, 2; E = Se, 3) and [AuI2{Se2P(OR)2}] (R = Et, 4; (i)Pr, 5) directly. We further demonstrate that this process is chemically reversible as all the Au(iii) complexes undergo chemical reductive elimination to the starting dinuclear Au(i) complexes in the presence of SnI2 as determined by (119)Sn and (31)P NMR. The complexes (2-5) were all prepared from the reaction between I2 and the corresponding dinuclear gold(i) precursor material. All new complexes were characterized by (1)H, (31)P, (77)Se (for E = Se) NMR, infrared spectroscopy, elemental analysis and single crystal X-ray diffraction.

Conformational analysis and stereochemical dependences of (31)P-(1)H spin-spin coupling constants of bis(2-phenethyl)vinylphosphine and related phosphine chalcogenides.

Theoretical energy-based conformational analysis of bis(2-phenethyl)vinylphosphine and related phosphine oxide, sulfide and selenide synthesized from available secondary phosphine chalcogenides and vinyl sulfoxides is performed at the MP2/6-311G** level to study stereochemical behavior of their (31)P-(1)H spin-spin coupling constants measured experimentally and calculated at different levels of theory. All four title compounds are shown to exist in the equilibrium mixture of two conformers: major planar s-cis and minor orthogonal ones, while (31)P-(1) H spin-spin coupling constants under study are found to demonstrate marked stereochemical dependences with respect to the geometry of the coupling pathways, and to the internal rotation of the vinyl group around the P(X)-C bonds (X = LP, O, S and Se), opening a new guide in the conformational studies of unsaturated phosphines and phosphine chalcogenides.